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KZ440 Won't Start After Top End Rebuild
- Jaytraeg
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My bike (1981 KZ440 LTD) was burning oil, so I took off the head and cylinder block to see what was going on. On inspection, the piston rings looked fine, the cylinders were a little glazed, and the valve stem seals looked fine. I had the cylinders honed, reused the rings, replaced the valve stem seals and all gaskets that were taken off with new ones. I made sure the bore and roundness were both in usable range, and reassembled completely according to the manual found on this website. Now, the bike won't start at all! It cranks, but no popping/banging/coughing like it even wants to start, even with starting fluid right in the cylinders.
Things to note:
-I didn't mess with the timing advancer except for setting the cylinders to TDC
-Valves were gapped to spec after reassembly
-Spark is good and strong
-Plugs are wet/smell like gas
-Oil was changed after rebuild
-Tried switching plug wires, but no change
-Battery was charged to full juice and is in good condition
-Gas is fresh, and carbs have gas in the bowls (plus were cleaned very thoroughly during the rebuild process)
-Looking in the spark plug holes while cranking, the valves are opening and closing smoothly
I'm stumped! Any ideas?
1981 KZ440 LTD
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- Nebr_Rex
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2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected
www.dotheton.com/forum/index.php?topic=39120.0
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- Jaytraeg
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1981 KZ440 LTD
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- baldy110
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- loudhvx
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www.kzrider.com/forum/2-engine/609860-kz...fter-rebuild?start=0
1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.
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- Jaytraeg
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1981 KZ440 LTD
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- OldguyJoe
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OP of the other thread here.
I just tonight found time to install the new coil, but the kids are sleeping and it's -11° outside, so a test run has to wait till morning.
Will gladly update you on the results.
Further, if you didn't remove the advancer or timing rotor during the rebuild, you don't have to worry about the 180° reversal thing.
Joe
1977 weird Canadian version of KZ400-s3
Had a 1973 Kawi 175 F3 trail bike in the 80s.
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- OldguyJoe
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Who knows what went wrong with the old one, as the engine ran great before the rebuild. Perhaps it had just enough oomph to spark with low compression.
Anyhow, I had good luck ordering the coil from this site's advertiser. I don't know which one you'd need, but surely someone here does.
Best of luck.
1977 weird Canadian version of KZ400-s3
Had a 1973 Kawi 175 F3 trail bike in the 80s.
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- loudhvx
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Jaytraeg's bike would use the same coil as you since you probably have a 440 or 750 twin ignition.
1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.
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- Jaytraeg
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Now I forget, did you say that your old coil still had an ohm reading that was considered within spec according to the manual? If so, how did you go about diagnosing the coil as faulty? That part of the thread was a little confusing to me.
In an case, looks like I'm going to spend part of the evening doing a resistance check on my coil. Thanks for the leads, guys!
1981 KZ440 LTD
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- loudhvx
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Jaytraeg wrote: I'm happy to hear that, Joe. Congratulations on your new working motorcycle!
Now I forget, did you say that your old coil still had an ohm reading that was considered within spec according to the manual? If so, how did you go about diagnosing the coil as faulty? That part of the thread was a little confusing to me.
In an case, looks like I'm going to spend part of the evening doing a resistance check on my coil. Thanks for the leads, guys!
I don't mean to answer for Joe, as he is perfectly capable, but as I understand it, he was getting good spark at the plugs in open air tests whenever he was kicking the motor over. But when he was doing long-spark tests by placing the plug bodies about 1/2" apart, he was just barely able to get spark. That does indicate a weakness in the coil or igniter (coil is more likely to fail), but it should have still been enough to start a normal motor, especially on ether. Perhaps it was a combination of a weak coil and low compression making it difficult to start?
I normally spray ether into the carbs so the ether only gets carried in with air, and is atomized.
1981 KZ550 D1 gpz.
Kz550 valve train warning.
Other links.
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- Jaytraeg
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The primary winding resistance (resistance between the two power terminals on the coil) measured at 2.0 ohms, which is out of the usable range specified in the service manual (3.2-4.8 ohms)
The secondary winding resistance (resistance between the two spark plug wires) measured at 11.3k ohms, which is in range of the 10.4k-15.6k ohm usable limit.
I think this is enough to condemn the coil, so I'll get a new one ordered. On the Z1 website, it says that using a coil with a slightly higher resistance is better than using one of slightly lower resistance (which I'm assuming is referring to the spec for the primary winding resistance listed above), so I'm thinking about getting the 5 ohm Dyna coil they have.
1981 KZ440 LTD
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